Device for the extraction of blood

ABSTRACT

The invention relates to a device for the extraction of blood comprising a sleeve and a piston which can be fabricated simply and economically and whereby the sleeve of which is suited for subsequent centrifugalizing in the same way as a conventional centrifuge tube. This invention is characterized in that a tube closed at one end is used as a sleeve and that a punctured piston is used having a tubular piston rod adjacent thereto, whereby at the free end of said piston rod projecting from the tube there are disposed lateral handles and the connecting socket for applying a tubule.

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PATEHTEHJUE: 3 [975 SHEET 1 DEVICE FOR THE EXTRACTION OF BLOOD Thisinvention relates to a device for the extraction of blood, comprising asleeve, a piston guided shiftabie and liquid-tight therein and a socketcommunicating with the interior for applying a tubule.

Such devices are known in the form of syringes which are also used toinject liquid. In recent times such syringes have been formed in such away, in particular in case they are used for extracting blood, that theyare used only once and then are disposed off. These syringes havealready been sterilized by the manufacturer and have been packagedsterile so that for the doctor the activity of sterilizing iseliminated. Also it is rendered impossible when using such syringes oncethat syringes already used are used a further time without a subsequentcleaning and sterilization or after an incomplete sterilization andresult in an infection of the secnd patient.

Provided blood is extracted from a patient with such syringes and is tobe centrifugalized, this blood is subsequently injected into acentrifuge tube. This tube is closed by a plug by the doctor or in thehospital and is transferred to the test laboratory, while the syringe isdisposed off.

in order to avoid the filling over required in this regard and to savethe special centrifuge tube, it has been proposed to use the sleeve ofthe syringe as a centrifuge tube, by closing the socket disposed at thebottom of this sleeve after removing the tubule with a special closurecap.

By the fact that the re-injection into a special centrifuge tube isdispensed with, a lesser haemolysis results and confusion and defilementpossibilities are eliminated. Also the centrifuge tubes are renderedsuperfluous.

The disadvantage of this single-use syringe for the extraction of blood,however, is that the bottom of the tube or of the sleeve greatlystresses in the centrifuge is closed by an applied closure cap which canhappen to detach or become untight in an adverse instance. In such acase the blood perhaps even containing germs would seep out of thebottom of the tube and would at least pollute the centrifuge, if notperhaps even the environment and depending on circumstances infect it.

Also there is the risk with this conventional single-use syringe thatthe socket after removing the tubule and prior to applying the closurecap is polluted during the manipulation and possibly is infected. Thiscould in the adverse case detrimentally affect the tests.

An object of this invention is to eliminate the disadvantages of theconventional devices and to provide a device for the extraction of bloodwhich is simple and economical to make and the sleeve of which is suitedfor a subsequent centrifugalizing in the same way as the conventionalcentrifuge tube, after removing the piston with the tubule.

This invention resides in the measure that as a sleeve a tube closed atone side and as a piston a punctured piston with an adjacent tubularpiston rod is used at the free end of which projecting from the tubethere are lateral handles and the socket for applying a tubule.

Prior to use, the piston is pushed completely into the tube, issterilized and is packed sterile. After puncturing the vein by thetubule the tubule and thus also the tubular piston rod and the pistonare held fixed by means of the handles, while the tube is drawn awayfrom the handle. Thereby in the interior of the tube a depressionresults which causes the entry of blood through the tubule via thetubular piston rod into the bottom area of the tube.

After extracting a sufficient quantity, the tubule is removed from thevein. The piston is drawn out of the tube, and the tube is closed by aplug before it is placed into the centrifuge. Prior to pulling thepiston out of the tube, the tubule can be removed, or it can also beleft on the socket. The blood contained in the tubular piston rod is notlost for the test, since it when pulling the piston out of the tube, issucked into the latter.

Since a subsequent refilling of the extracted blood into a centrifugetube is omitted, the haemolysis is maintained to a minimum possiblerating.

The use of additional centrifuge tubes next to the sleeve of the deviceis dispensed with or this sleeve is defined by the normal centrifugetube.

In certain applications and in particular for devices according to themain patent in which for the extraction of larger amounts of blood thetube accomodating the piston has a larger diameter, it has proven to bedesirable to not arrange the connecting socket for applying an injectionneedle concentric relative to the tube, ie in a greater spacing from thecircumference thereof, but eccentric, namely as closely as possible tothe circumference of the tube. For this affords substantial advantagesupon introducing the injection needle in a vein and the subsequentextraction, for manipulation, because now the tube can be held parallelto the surface of the arm or the like along its entire length and adisturbed holding and thus the risk of an injury of the opposing veinwall with an inclined holding is not provided or is hardly providedanymore.

While now in the conventional blood extraction devices in which theconnecting socket is arranged at the end of the tube, i.e., the socalled syringe cylinder, and the piston is not bored through, such aneccentric embodiment can be easily provided because of the arrangementof the injection syringes in several parts, this is not possible becauseof certain difficulties in manufacture for the device according to themain patent in which the piston, the piston rod, the handle and theconnecting socket for the injection needle are injection molded in onepiece of plastic.

The device for extracting blood, therefore, preferably is furthered insuch a way that the piston includes a thin circular disk connected tothe guide veins and a thin circular cylindrical collar projecting fromthe circumference thereof in axial direction.

Even in case of a deviation of the circumference of the circular diskfrom the desired circular shape the collar projecting from it alwayswill attempt to have its circular cylindrical shape. The collar thuswill in all events sealingly engage the inner surface of the tube, inparticular with its free edge, even in case of deviations of the diskfrom the circular shape. By this configuration of the piston thedifficulties are eliminated which result in the manufacture of thepiston with the piston rod in one piece.

Here also guide wings are provided which extend outwardly from thetubular piston rod and take over the guiding of the piston rod in thetube.

Preferably the bottom of the sleeve can be filled with a substancesuppressing a blood coagulation. This substance may also be applied tothe inner wall of the tubular piston rod.

It is preferably provided for in this regard that the tubular piston rodconically converges from the opening in the piston toward the socket.Thereby, a gradual transition from the large cross section of theopening in the piston to the small cross section of the tubule or viceversa is provided for. By this flow enhancing configuration the risk ofan haemolysis is again reduced.

ln order to accomplish a satisfactory guiding of the piston and thepiston rod in the tube and in order to prevent a cocking, it isfurthermore proposed to provide at least three guide wings extendingradially outwardly from the piston rod and extending in the longitudinaldirection thereof, said guide wings with their outer edges extendingparallel to one another and to the longitudinal axis of the piston rodand defining an enveloping cylinder which corresponds to the inner peripheral wall of the tube. The piston can now be formed as a simplecircular disc, and an excellent guiding and sealing effect isaccomplished in particular in case the piston, the piston rod and theguide wings are made of a resilient plastic. The tube can be made in amanner known per se either of glass or of a plastic.

According to this invention a plug of resilient material is associatedto the tube, said plug having a knob and an adapter portion adjacentthereto which has a peripheral surface sealingly fitting into thecylinder and a tapered axial bore adapted to the tapered socket of theplunger, said axial bore being closed at its inner reduced end. Thisplug is formed in such a way that it greatly facilitates themanipulation of the device. Devices of this type are supplied with aninserted plunger and packed sterile. In order to prevent a defilement ofthe bore of the plunger prior to applying a sterile injection needle, acap can be applied to this socket. Also a plug is required after theextraction of blood for closing the tube, after the plunger togetherwith the injection needle has been removed out of the tube. The plug ofthis invention now combines this cap and the closure plug in a singlemember. The plug thus with its tapered axial bore initially plugs thesocket at the free end of the plunger and later after the removal of theplunger from the tube plugs this tube with its larger adapter portion.

In order to improve the sealing effect, the peripheral surface of theadapter portion is formed slightly tapered. Preferably an annular beadprojects radially outwardly from the peripheral surface of the adapterportion which likewise improves the sealing effect. Alternatingly, aplurality of annular beads may be provided also.

The tapered bore at one end of the plug is preferably defined by ahat-shaped recess extending axially inwardly. Then the plug otherwisecan be formed generally hollow so that its weight and thus also itsprice can be kept low.

Depending on whether the blood extracted from a patient is to coagulateand then its constituents are to be examined further or whether theblood is supposed to be centrifugalized without coagulating, it isfilled in present day practice from the extraction device into acentrifuge tube or some other container. With the device of thisinvention the centrifugalizing or also the coagulation process can nowbe effected in the same tube in which the socket is disposed with theapplied injection needle after the removal of this socket.

In order to separate as satisfactorily as possible the two fractions ofthe blood forming upon centrifugalizing or upon coagulating, the deviceaccording to this invention has been developed further in such a waythat a chemically inert granulate is added to the tube as a separatingagent. This granulate thus is contained in the device packaged sterilecomprising the tube and the socket pushed thereinto.

The separating agent assumes a position between the two fractions in thelater separation of the blood, be it during coagulation, be it alsoduring centrifugalizing, thus facilitating the examination of one ofthese two parts alone. The advantage of the combination of the tube withthe socket and the separating agent is that thereby a complete device isprovided ready for use and that thereby the servicing is extremelyfacilitated, in particular a refilling is rendered superfluous.

Prior to using the device, it is preferably sterilized inclusive theseparating agent and packaged sterile.

When drawing the blood quantity in, it directly encounters theseparating agent disposed in the bottom area of the tube.

The granulate filled into the tube preferably comprises a plastic thespecific weight of which is between that of the blood cake and that ofthe serum, i.e. between the specific weights of the two fractions. As aresult thereof the separating agent properly assumes a position betweenthe two constituents and separates them from one another.

Furthermore it is proposed to introduce into the tube of the device forthe extraction of blood a granulate of a chemically inert substance, thegrains of this granulate being coated with a chemical substance at theirsurface which either accelerates the blood coagulation or, in case thisis desired, retards the blood coagulation. Thus, by using variousgranulates either immediately an accelerated coagulation can be causedso that the examination of the two fractions can be effected earlierthan up to now. But on the other hand any blood coagulation can beprevented from the start on by applying a coagulation retardingsubstance to the surface of the granulate grains so that the bloodextracted immediately contacts this coagulation retarding substance.

By the fact that the said chemical substance is pro vided in a thinlayer on a relatively large surface, namely the overall surface of allgrains of the granulate, this substance has a particularly quick effect.Substances which retard or accelerate the blood coagulation, of course,have been known already and have also already been used for thispurpose, but not as a coating on a granulate as a vehicle which isdirectly filled into the device for the extraction of blood. Thisgranulate can also at the same time be provided as a separating agent asmentioned hereinbefore.

According to this invention it is furthermore proposed to not coat thesurface of the granulate grains with a chemical substance in a thinlayer in order to thereby influence the coagulation of the blood, ratherit is proposed, for accelerating the coagulation of the blood, that inthe surface proximate layers of the granulate grains small glassparticles, preferably glass fibres, are embedded. These glass particlesprojecting from the surface of the granulate grains have a purelyphysical effect, by influencing the surface tension at the interface, onthe blood coagulation. it has been observed that the blood coagulationproceeds slower in vessels of thermoplastic materials, in particular ofpolyethylene and polypropylene, than in vessels of glass. ln someinstances such a delay in the blood coagulation is utterly undesired. Upto now then the use of plastic vessels instead of glass vessels had tobe dispensed with, although plastic vessels have many other advantages.The glass particles introduced in the surface of the granulate grainsaccording to this invention now bring about substantially acceleratedblood coagulations. By a metered addition of these glass particles orthe granulate grains provided with such glass particles the bloodcoagulation can now be accelerated in any desired way, or the slowingdown of the blood coagulation can merely be compensated which resultswhen using tubes of plastic, so that thereby blood coagulation ratingsare obtained like they result in glass tubes.

Provisions are thus available with these granulate grains includingembedded glass particles to arbitrarily accelerate the blood coagulationwithout having to use chemical substances which perhaps might interferespecific tests.

It is essential for the effect of the granulate proposed according tothis invention that the glass particles project from the surface of thegranulate grain carrying them without themselves being encased andcovered by the substance of the granulate.

A plastic granulate of a conventional grain size is particularly suitedfor this purpose like it is used for charging plastic processingmachines, for instance extruders. Basically all plastics are suited forthis provided they are not objectionable for chemical reasons andinterfere the blood examination. Fine glass particles, for instanceshort fibres of glass, are then to be included in the individual grainsof the granulate. Such plastic granulates or intermediate products ofplastic which are enforced by glass fibres or glass particles are knownalready. They are suited as an aid for the examination of blood in thesense of the invention only in the event the glass particles, forinstance the ends of the glass fibres, project outwardly from thesurface of the plastic particles and thus become physically effective.It is to be observed when producing such granulates that the glassparticles or at least some of them project outwardly from the surface.

This invention is explained hereinafter in embodiments in referring tothe drawing. Therein:

FIG. 1 is a longitudinal sectional view of the device of this invention;

FIG. 2 is an enlarged cross sectional view along the line 11-" in FIG.1;

FIG. 3 is a sectional view of a modified device with an eccentric duct,in a section along line III-III of FIG.

FIG. 4 is a sectional view along line IV-IV of FIG 3;

FIG. 5 is a device similar to the device illustrated in FIG. I, in aside elevation of view, with applied plug;

FIG. 6 is a sectional view of the plug in FIG. 5 and of the conicalsocket of the plunger;

FIG. 7 is a sectional view along line VII-VII of FIG.

FIG. 8 is a sectional view of the plug as illustrated in FIG. 6, butinserted in the end of the tube;

FIG. 9 is a simplified sectional view of a tube of the device in thefilled condition; and

FIG. 10 is a sectional view in an enlarged scale of a granulate particlewith embedded glass fibres.

The device illustrated in FIG. 1 comprises a tube 1 closed at one side,a socket inserted therein, which includes a tubular piston rod 2, fourlateral guide wings 3 and at their lower end a disc-shaped piston 4, tworadially outwardly projecting handles 5 which are to facilitate themanipulation of the device, and a connecting socket 7 for applying thecap 8 of an injection needle 9. The piston 4, the tubular piston rod 2,the guide wings 3, the connecting socket 7 and the handles 5 are made inone piece and preferably of a resilient plastic, for instancepolypropylene.

The tube can be made in a conventional way of glass or also of aplastic, for instance of polystyrene.

As will be noted from FIG. 2, the guide wings 3 closely engage the innerperipheral wall of the tube I with their outer edges and thereby guidethe piston properly in the tube.

The modified embodiment illustrated in FIGS. 3 and 4 of the bloodextraction device again includes a tube 101 closed at one side, aplunger 102 shiftable in a hermetically sealing fashion in this tube, atubular plunger rod 103 connected thereto and at the end thereof ahandle 109 as well as a connecting socket 110 for applying an injectionneedle.

The piston comprises a thin circular disc 111 which may possiblyslightly deviate from the circular shape in manufacture, and a thincircular cylindrical collar 112 projecting from the periphery thereof inaxial direction, said collar taking over the sealing function inrelationship to the tube 101.

The bore 104 through the circular disc 111 and the plunger rod 103connected thereto are arranged concentrical in relationship to thecentral axis of the tube 101. Accordingly the connecting socket 110 forapplying an injection needle also is disposed relatively closed to thecircumference of the tube 101.

Guide wings 105, 106, 107 and 108 extend from the plunger rod 103outwardly to the inner wall of the tube. These veins have differentlengths because of the eccentric position of the plunger rod.

In the device illustrated in FIG. 5 a plug 10 is disposed on theconnecting socket 7a and has a knob 12 which at the outside is providedwith corrugations or the like. An adapter portion 11 is provided axiallyadjacent to the knob and has a radially projecting narrow annular beadl4.

Otherwise the device according to FIG. 5 again comprises a tube la, atubular piston rod 2a with guide wings 3a and handles 5a as well as adisc-shaped piston 40 at the free end of the piston rod 20. Theconnecting socket 7a serves to apply the cap of an injection needle whenpreparing the device for use.

It will be noted from the sectional view of FIG. 6 that the plug 10 isformed generally hollow and has a conical inverted portion 15 settingout from the bottom of the adapter portion 11. This inverted portion hasan inner conical peripheral surface which is adapted to the conicalouter peripheral surface of the socket 7a of the plunger. With the plugapplied thus the longitudinal bore 6a of the plunger and of the socket7a is covered and closed by the hat-shaped inverted portion 15.

As will be noted from FIG. 6 in conjunction with FIG. 7, thecomparatively thin walls of the knob 12 of the plug are supported byfour radial walls 13 which at their lower or inner end, as will be notedfrom FIG. 6, are connected to the closed end of the inverted portion 15and thereby are also supported in relationship to this inverted portion.Thereby a great increasing of the strength of the plug is accomplishedeven with a thinwalled configuration. On the other hand the thinwalledconfiguration facilitates the scaling in the vicinity of the annularbead 14 of the adapter portion 11.

A granulate 16 of plastic, acting as a separating agent, is filled intothe tube la.

The sectional view of FIG. 8 shows how the adapter portion 11 of theplug is inserted in the upper opening of the tube la and how the annularbead 14 in doing so causes a reliable sealing effect. it will be notedthat the adapter portion 11 is radially offset at the junction to theknob 12 relative thereto. The shoulder defined thereby serves as anabutment when inserting the plug in the tube la.

In FIG. 9 finally the tube lb of a device of this invention has beenillustrated filled with a blood sample. The figure shows the bloodsample after centrifugalizing. in the lower portion of the tube thesedimented bloodcorpuscles 19 are disposed, thereabove the separatinglayer 18, comprising the granulate acting as a separating agent, whichat its surface was coated with a substance retarding the bloodcoagulation, thereabove the liquid plasma 17.

The same picture virtually results when the blood is caused to coagulateand the blood is then centrifugalized. Then the coagulated blood cake isdisposed at the bottom of the tube, thereabove the separating agentlayer and thereabove the liquid serum. in this case preferably aseparating agent is used with a chemical substance for accelerating theblood coagulation or with embedded glass particles which have the sameeffect. Various chemical substances are known which chemically have aneffect on the blood coagulation process and accelerate it.

But it also known that the blood coagulation can be influenced byphysical means. For instance blood coagulates slower in vessels ofthermoplastic materials than in vessels of glass, which is to beexplained by the different surface tension and the physical conditionsat the interface between the blood and the container wall.

in furtherance of the invention it is not proposed that the substanceaccelerating the blood coagulation and disposed on the top surface ofthe granulate grains is glass, namely in the form of fine particles, inparticular fibres, which are embedded in the outer layer of eachgranulate grain. Principally all plastics are suited for such agranulate, provided they do not interfere with the blood examination forchemical reasons. The glass fibres are to project outwardly from thesurface of the plastic parts, in order to become physically effectivetherewith. in FIG. such a granulate particle 20 has been illustrated toan enlarged scale, namely in cross section to the left side of thesection line A--A and in a elevation of view at the right hand of thisline. The glass fibres 21 embedded irregularly in the granulateparticles 20 will be noted which project from the surface of thegranulate particle 20.

What is claimed is:

1. A device for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston rod extending from said piston in communication with the aperturetherein and extending out through said tube open end, said piston beingin sealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, said hollow piston rod has a tapered bore, saidbore decreasing in cross section from said piston towards said free endwhereby a maximum suction is effected at said piston rod free end.

2. A device for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston rod extending from said piston in communication with the aperturetherein and extending out through said tube open end, said piston beingin sealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, said hollow piston rod is tapered from saidpiston to said free end, and said piston rod has a similarly taperedbore whereby a maximum strength to weight ratio is obtained togetherwith a maximum suction being effected at said piston rod free end.

3. A device for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston road extending from said piston in communication with theaperture therein and extending out through said tube open end, saidpiston being in sealed engagement with the interior of said tube andsaid piston rod having axially elongated generally radially extendingwings guidedly engaging the interior of said tube, said piston rodhaving a free end in the form of means for the reception of a needle insealed engagement, a transversely disposed handle on said piston rodadjacent said free end for withdrawing said piston assembly from saidtube to produce a suction within said piston rod, a plug of resilientplastic, said plug having a knob and an adapter portion axially adjacentthereto, said adapter portion having a peripheral surface sealinglyengageable with said tube and a conical axial bore receiving said pistonrod free end, said axial bore being closed at its inner end.

4. Device according to claim 3, characterized in that at least oneannular bead projects radially outwardly from the peripheral surface ofthe adapter portion.

5. Device according to claim 3, characterized in that the conical boreis defined by a hat-shaped inverted portion extending from the free endof the adapter portion axially inwardly.

6. A device for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston rod extending from said piston in communication with the aperturetherein and extending out through said tube open end. said piston beingin sealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, a granulate in said tube between said piston andsaid tube closed end, said granulate being a chemically inert substancefor functioning as a separating agent between two blood fractions, andincluding surface proximate layers with embedded small glass particles,preferably fibres, partially projecting outwardly from the surfacethereof.

7. A device for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston rod extending from said piston in communication with the aperturetherein and extending out through said tube open end, said piston beingin sealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent, said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, a granulate in said tube between said piston andsaid tube closed end, said granulate being a chemically inert substancefor functioning as a separating agent between two blood fractions, andthe particles of said granulate having a coating of a substance forretarding blood coagulation.

8. A device for the extraction of blood by means of a suction effect,said device comprising a tube having a closed end and an open end, a onepiece integrally molded piston assembly cooperatively telescoped withinsaid tube, said piston assembly comprising an inverted cup shapedpiston, a tubular rod, axially extending guides, and handle means; saidcup shaped piston having a cylindrical portion in sliding sealedengagement with said tube and an end wall, said tubular piston rod beingcarried by said piston end wall in eccentric relation to said piston andtube and projecting out of said tube, said piston rod having a free end,means only at said free end for the mounting of a needle thereon, saidaxially extending guides projecting generally radially from said pistonrod and guidedly engaging said tube, at least two of said buides beingof appreciably different radial dimensions due to the eccentricity ofsaid piston rod relative to said tube, a bore in said piston end wall incommunication with the interior of said piston rod, and said handlemeans on said piston rod being adjacent said free end.

9. A device for the extraction of blood by means of a suction effect,said device comprising a tube having a closed end and an open end, apiston assembly cooperatively telescoped within said tube, said pistonassembly comprising an inverted cup shaped piston having a cylindricalportion in sliding sealed engagement with said tube and an end wall, atubular piston rod carried by said piston end wall in eccentric relationto said piston and tube and projecting out of said tube, said piston rodhaving a free end portion defining means for the mounting of a needleaxially extending guides projecting generally radially from said pistonrod and guidedly engaging said tube, a bore in said piston end wall incommunication with the interior of said piston rod, handle means on saidpiston rod adjacent said free end, said piston rod is conically reducingin cross section from said piston toward said free end whereby at leasttwo of said guides taper in opposite directions relative to each otherand to the length of said piston rod.

1. A device for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston rod extending from said piston in communication with the aperturetherein and extending out through said tube open end, said piston beingin sealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, said hollow piston rod has a tapered bore, saidbore decreasing in cross section from said piston towards said free endwhereby a maximum suction is effected at said piston rod free end.
 1. Adevice for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston rod extending from said piston in communication with the aperturetherein and extending out through said tube open end, said piston beingin sealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, said hollow piston rod has a tapered bore, saidbore decreasing in cross section from said piston towards said free endwhereby a maximum suction is effected at said piston rod free end.
 2. Adevice for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston rod extending from said piston in communication with the aperturetherein and extending out through said tube open end, said piston beingin sealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, said hollow piston rod is tapered from saidpiston to said free end, and said piston rod has a similarly taperedbore whereby a maximum strength to weight ratio is obtained togetherwith a maximum suction being effected at said piston rod free end.
 3. Adevice for the extraction of blood by means of a suction effectcomprising a tube having a closed end and an open end, a one-piecepiston assembly cooperatively telescoped within said tube, said pistonassembly comprising a piston having an aperture therethrough, a hollowpiston road extending from said piston in communication with theaperture therein and extending out through said tube open end, saidpiston being in sealed engagement with the interior of said tube andsaid piston rod having axially elongated generally radially extendingwings guidedly engaging the interior of said tube, said piston rodhaving a free end in the form of means for thE reception of a needle insealed engagement, a transversely disposed handle on said piston rodadjacent said free end for withdrawing said piston assembly from saidtube to produce a suction within said piston rod, a plug of resilientplastic, said plug having a knob and an adapter portion axially adjacentthereto, said adapter portion having a peripheral surface sealinglyengageable with said tube and a conical axial bore receiving said pistonrod free end, said axial bore being closed at its inner end.
 4. Deviceaccording to claim 3, characterized in that at least one annular beadprojects radially outwardly from the peripheral surface of the adapterportion.
 5. Device according to claim 3, characterized in that theconical bore is defined by a hat-shaped inverted portion extending fromthe free end of the adapter portion axially inwardly.
 6. A device forthe extraction of blood by means of a suction effect comprising a tubehaving a closed end and an open end, a one-piece piston assemblycooperatively telescoped within said tube, said piston assemblycomprising a piston having an aperture therethrough, a hollow piston rodextending from said piston in communication with the aperture thereinand extending out through said tube open end, said piston being insealed engagement with the interior of said tube and said piston rodhaving axially elongated generally radially extending wings guidedlyengaging the interior of said tube, said piston rod having a free end inthe form of means for the reception of a needle in sealed engagement, atransversely disposed handle on said piston rod adjacent said free endfor withdrawing said piston assembly from said tube to produce a suctionwithin said piston rod, a granulate in said tube between said piston andsaid tube closed end, said granulate being a chemically inert substancefor functioning as a separating agent between two blood fractions, andincluding surface proximate layers with embedded small glass particles,preferably fibres, partially projecting outwardly from the surfacethereof.
 7. A device for the extraction of blood by means of a suctioneffect comprising a tube having a closed end and an open end, aone-piece piston assembly cooperatively telescoped within said tube,said piston assembly comprising a piston having an aperturetherethrough, a hollow piston rod extending from said piston incommunication with the aperture therein and extending out through saidtube open end, said piston being in sealed engagement with the interiorof said tube and said piston rod having axially elongated generallyradially extending wings guidedly engaging the interior of said tube,said piston rod having a free end in the form of means for the receptionof a needle in sealed engagement, a transversely disposed handle on saidpiston rod adjacent, said free end for withdrawing said piston assemblyfrom said tube to produce a suction within said piston rod, a granulatein said tube between said piston and said tube closed end, saidgranulate being a chemically inert substance for functioning as aseparating agent between two blood fractions, and the particles of saidgranulate having a coating of a substance for retarding bloodcoagulation.
 8. A device for the extraction of blood by means of asuction effect, said device comprising a tube having a closed end and anopen end, a one piece integrally molded piston assembly cooperativelytelescoped within said tube, said piston assembly comprising an invertedcup shaped piston, a tubular rod, axially extending guides, and handlemeans; said cup shaped piston having a cylindrical portion in slidingsealed engagement with said tube and an end wall, said tubular pistonrod being carried by said piston end wall in eccentric relation to saidpiston and tube and projecting out of said tube, said piston rod havinga free end, means only at said free end for the mounting of a needlethereon, said axially extending guides projecting generally radiallyfrom said piston rod and Guidedly engaging said tube, at least two ofsaid buides being of appreciably different radial dimensions due to theeccentricity of said piston rod relative to said tube, a bore in saidpiston end wall in communication with the interior of said piston rod,and said handle means on said piston rod being adjacent said free end.